The U.S. Fish and Wildlife Service (FWS) removed federal protections for the wolves (Canis lupus) in 2012. The agency concluded that the canids had fully recovered from near-extinction and turned their management over to the three states’ wildlife departments. But in her 19 December ruling, U.S. District Judge Beryl Howell called the decision “arbitrary and capricious.”

At the time of the wolves’ delisting, federal wildlife biologists estimated the animals’ population in the region at 4400. That number dropped to 3748 this year as a result of hunting and trapping, and state plans called for an even greater decline. For instance, Wisconsin’s Department of Natural Resources was aiming for a statewide wolf population of just 350 animals (from a high of 800).

In response, the Humane Society of the United States, representing a coalition of animal rights and conservation organizations, filed suit against the U.S. Department of the Interior in 2013. They argued that the decision to remove federal protections was premature and threatened the wolves’ survival.

Howell agreed, finding that FWS had incorrectly interpreted the ESA by not assessing the species as a whole. The agency’s delisting decision was “fatally flawed,” she wrote, because it was tied to “a scientific finding that turned out to be, at best, premature, or, at worst, erroneous.”

FWS spokesman Gavin Shire disagreed, saying that the “science clearly shows that wolves are recovered in the Great Lakes Region, and we believe the Great Lakes states have clearly demonstrated their ability to effectively manage their wolf populations.” FWS has not yet decided if it will appeal the ruling.